Tuesday, April 23, 2013

Social Priming: In Theory

You are walking into a room. There is a man sitting behind a
table. You sit down across from him. The man sits higher than you, which makes
you feel relatively powerless. But he gives you a mug of hot coffee. The warm
mug makes you like the man a little more. You warm to him so to speak. He asks you about your relationship
with your significant other. You lean on the table. It is wobbly, so you say
that your relationship is very stable. You take a sip from the coffee. It is
bitter. Now you think the man is a jerk for having asked you about your
personal life. Then the man hands you the test. It is attached to a heavy
clipboard, which makes you think the test is important. You’re probably not
going to do well, because the cover sheet is red. But wait—what a relief!—on
the first page is a picture of Einstein! Now you are going to ace the test. If
only there wasn’t that lingering smell of the cleaning fluid that was used to
sanitize the room. It makes you want to clean the crumbs, which must have been
left by a previous test-taker, from the tabletop. You need to focus.
Fortunately, there is a ray of sunlight coming through the window. It leaves a
bright spot on the floor. At last you can concentrate on the test. The final
question of the test asks you to form a sentence that includes the words gray,
Florida, bingo, and pension. You leave the room, walking slowly…

These are just some findings that have been reported in the
literature (well, most of them are; I made one up, guess which one) on social
priming. But I don’t want to focus on the findings themselves in this post.
What I want to do is find out what the theory behind them is. The picture
suggested by social priming research is that we are constantly bombarded with a
cacophony of cues in all sensory domains that push our behavior around in
various ways. This cannot be true.

In a 2006 paper, John
Bargh, by all accounts the major player in the area of social priming, arrived
at very much the same conclusion. What
have we been priming all these years?, he asks. To address the cacophony
problem, Bargh suggests that all cues are not created equal. Cues related to
goals trump other cues. For example (this is my example, not his), you may be
walking slowly out of the room after having just formed a sentence that
includes gray, Florida, bingo, and pension but as soon as someone yells
FIRE!, you are bound to make a dash for the nearest exit. Your
self-preservation goal has trumped whatever priming you may have received from
the sentence-unscrambling task.

This makes sense. Bargh also provides a useful overview of
the history of priming. Although priming is a concept from cognitive
psychology, Bargh is right in criticizing classical cognitive science in its treatment
of priming. Classical cognitive science has mostly been interested in priming
words. For example, you recognize the word doctor
faster after having just seen nurse
than after having just seen bread. Although this has provided useful insights
into the organization of memory, inference generation, false memories, speech
errors, and so on, there is no clear behavioral component. The behavior on the
subject’s part is limited to pressing a button. Bargh does not think this counts
as real behavior. And who can blame him? His goal is to examine how priming
affects not just thinking but also action, a goal that has also been adopted in
contemporary cognitive psychology and cognitive neuroscience.

Bargh observes another difference between classical cognitive psychology
and social cognition. The classical priming experiment examines words as primes
and as targets (the recognition of a word is often the dependent measure). In
social cognition complex conceptual structures are primed that have
action components associated with them. Whereas a classical priming experiment
may want to investigate whether gray
primes old, a social priming
experiment wants to know whether priming with gray and old will
influence the speed of subsequent action. Despite its strong points, the Bargh
article is rather low on specifics regarding the mechanisms of priming and the
representations that are involved.

Enter a recent Psychological
Reviewpaper
by Stroeber and Thagard. They provide a computational model of social priming.
A key concept in their model is constraint satisfaction. To illustrate this,
let me introduce you to your long-lost cousin Lars from Sweden. He used to live
on a small island in the middle of a lake that is frozen over much of the year.
His close relatives live in villages all around the lake. Did I tell you he
died? How sad, you just learned you had a lost relative and now you find out
he’s already dead. Among Lars’ possessions was a very expensive grand piano,
which is coveted by all of his relatives. They’ve put the piano on the ice and
are now each trying to push the valuable musical instrument to their side of
the lake. Björn
and Bennie are very interested in the piano but being musicians, they are not
very strong and they cannot get the piano to move in their preferred direction
(if only they had Agneta and Frida to help them!). Their cousin Knut is a
hockey player and is pushing the piano in a different direction. Other
relatives are pushing in yet other directions. Which way will the piano go? It
is basically the sum of all the force vectors. Because people will not be able
to apply constant force, the piano’s path will not be a straight line—until the
weakest relatives get tired. And then, slowly but surely, the piano will move
in the direction of Knut’s log cabin.

That’s how constraint satisfaction works. Each relative constrains
the path of the piano just like each cue constrains the course of action. Some
cues will be stronger than others. And some cues will have longer-lasting
effects than others. The system handles the cacophony of cues through
constraint satisfaction. Sometimes a cue is so strong that it wins out
immediately over all the others, as in the case when someone yells FIRE!. The cousin-Lars-analogy
of this would be if someone donned an Iron Man suit and then started pushing
the piano. The others might as well give up right away.

In line with Bargh’s notion of priming, the model assumes that
primed concepts activate holistic representations of situations, which have
psychological, cultural, and biological components. These layers mutually
constrain each other. The way in which they do this is acquired during
socialization. Because concepts have affective meanings, they can generate
responses automatically. Affective meanings are organized in culturally-shared
structures (meaning that responses will be similar across individuals). Members
of a culture will try to maintain these structures, which produces a set of constraints.

So how does this cause behavior? Priming activates neural
populations that act as “semantic pointers” to underlying sensorimotor and
emotional representations. This is the biological component of the model. The
idea is very much in the vein of Damasio’s convergence
zones.

So the model is an account of how a simple prime in one modality
may give rise to a range of responses, some purely cognitive, some emotional,
and some behavioral.

I realize that I’m not doing the model much justice in this brief
description but my point is that it apparently is possible to come up with a
plausible model of social priming that is relatively detailed in parts and is consistent
with current models of memory and action.

It is of course ironic that the model has been developed to
explain findings that have proven so difficult to replicate and have raised so
much controversy. Nevertheless, the model provides an interesting and rather
detailed account of how social priming works in theory. Now it would be
interesting to see if it can generate novel predictions that can be tested in
rigorous experiments.

13 comments:

You've made me curious to read the new psych review paper. I got a chance to talk to Thagard several times a few years ago while I was doing a post-doc at Waterloo, he's a really interesting guy and I think constraint satisfaction is a very useful way of looking at a lot of social reasoning. (Thagard and I wrote a short chapter together that's coming out soon on how constraint satisfaction can help explain both paranoia and irrational exuberance though self-reinforcing feedback loops.)

I think one thing that I'd add on priming, which makes your introductory paragraph sound so absurd (intentionally, obviously), is that it seems to me that priming only makes much difference when whatever is being primed is relevant to the person at the time.

For example (assuming all these examples are true, for the moment), if I smell cleaning fluid, it might make me a little more likely to clean up crumbs if there are some in front of me, but I wouldn't go looking for them in another room. If my chair is wobbly, I won't spontaneously attribute that to my relationship (which one even?) -- but if I'm specifically asked, and I try to retrieve my feelings about it, only then will the wobbliness potential come into the equation. This is one reason why we're not constantly overwhelmed by primes pushing us in a thousand different directions.

One thing that seems important to me to separate in the priming literature may be an artifact of the current scientific culture. Namely, I think that the difficult-to-replicate priming effects are the ones that are purposely surprising and difficult to find. (This also means that they are, given the current state of the science, more vulnerable to false positives.)

I feel quite confident that we are strongly primed all the time, but by very strong primes. However, these strong primes are often confounded with other things (for example, if I smell french fries and 10 minutes later I want to go to McDonalds, it could be because I explicitly made the decision to go).

But more importantly, they are also not as interesting and therefore less likely to get publish or generate attention. And so the publications that we see are these carefully designed minimal primes -- I don't think that means that behavioral priming itself is hard to find. If the man sitting across the table from you reminds you of your best friend growing up, you're probably more likely to comply with his requests than if he reminds you of someone you don't like. The warm cup of coffee in your hand may help too, but it has a much more challenging path.

Since I'm autistic, I'm hyper-alert to all the sensory cues you mention. It seems to me that most autistic people live a bimodal existence; either easily distracted/flustered by an overload of sensory input, or totally focused on the task at hand, completely excluding all extraneous inputs. I'd be interested to know (assuming you are able to construct the tests you mention) if the results would be markedly different for neuroexceptional people (including not just autism but also related profiles like bipolar, schizophrenia, and dyslexia).

Autism is normal, just not typical. Of course there are large individual variations in just about everything. In doing controlled studies, the question is always whether there are differences in the means of the distributions of whatever is being measured.

Great post. Wouldn't the constraints model predict precisely that priming effects be difficult to replicate? If primes represent the culturally learned affective component of concept all pushing among one another than they should be highly subject to individual and cultural differences. Precisely at what level of specificity is an interesting question. Will white college students prime differently than black urban workers? Will Danes prime differently from Swedes? At some level what we are talking about here is the relationship between learning and conscious perception; should we be surprised that some labs can find big effects here and others can't? Small shifts in experimenter-experimentee relations, cultural setting, etc would all have a huge impact on the actual effect if the constraints model is correct.

Good points. To my mind, the strongest constraint would still be the subjects' knowledge and experience regarding the task at hand. These may or may not be nudged a little bit by social primes (at least of the type we're talking about here. See my next post for a discussion of stronger primes). Let's suppose for a moment the walking-speed finding is true. Then I would think that people would walk out of the lab slightly slower than at their usual speed. I'd expect normal walking speed to predict far more of the variance than priming condition.

I think one of the reasons priming effects are so difficult to replicate is that such priming effects involve something like a conspiracy of the weak: Multiple sources of weak constraints conspire to eventually produce a detectable effect, but each constraint in and of itself is so weak that it fails to register. That would also account for the observed variability in obtaining such effects.

Thanks for pointing me to this post - and to the review paper. I should read this. Sounds like just the kind of theoretical account that I think this line of research needs a lot more of. Presumably with all the different vectors pulling in all sorts of directions you should see very subtle effects, well below d=1...